PV devices convert sunlight into electricity via a physical process called “photovoltaic effect.” Specifically, sunlight is composed of photons, or “packets” of energy. The photons contain various amounts of energy corresponding to different wavelengths of light Upon striking a PV device, a photon may be reflected, absorbed, or pass right through the device. When a photon is absorbed, the energy of the photon is transferred to an electron in an atom of a semiconductor within the PV device. With its newfound energy, the electron is able to escape from its normal position associated with that atom. By leaving this position, the electron causes a hole to form. Electrons and holes thus formed are collected each by one of two separate electrodes. The PV device can then be used to power an external electrical device using the two electrodes.
Different parameters can be used to evaluate a PV device's efficiency. Among these parameters is the device's short-circuit conductance GSC. The GSC is used to evaluate the amount of electrical loss caused by the device's shunt resistance. The greater the GSC, the more shunted the device and the less power that the device can produce.
As will be explained later, the GSC of a PV device is related to the device's short-circuit current ISC, which is the current through the device when the voltage through the device is zero. Thus, knowing the ISC of a PV device, its GSC can easily be determined.
Traditionally, a simulator is used to determine the ISC of a PV device. This usually occurs after the device has been manufactured and during a simulation stage. However, due to limitations in simulators, the determined ISC and thus the GSC of a PV device are not always accurate. Therefore, methods and systems are desired for more accurately determining the ISC and GSC of a PV device.